Iphone 4: weird buzz sound with turned off 3G

I live in an area where 2G is stronger than 3G (I seem to get 1 more bar when I turn off 3G). However, once I do that I get a weird buzz sound (like there was a static interference). Its the same kind of sound you here from computer speakers when you place a phone near them. But I tested it away from potential interference sources. Once I turned on 3G, the voice was clean and there was no more buzz sound!

I hear those sounds on low when I put the phone to my head. When I use the speakerphone I hear no static sounds.

I had Blackberry Curve 8310 before with ATT that did calls on 2G only and never had this issue.

I am using phone without case waiting for a free one in the mail, but I don't hold the bottom and it still does that.

Should I take it to Apple Store and diagnose it? Did you have the same problem?

Re: Iphone 4: weird buzz sound with turned off 3G

I checked the phone in more places and I noticed that this buzz (static noise) happens only in certain places. In places where I had constant 5 bars while talking the sound was clear. When I checked this orgininally and got this noise this was in area where I have 3 bars.

However, still with Blackberry even with 2 bars or only 1 I had no such thing.

Either all iPhones have this bug or my model is particulary defective but it shouldn't be.